Cyclobutyl phenyl sulfoxide and (SR)-cyclobutyl p-tolyl sulfoxide: New reagents for the spiroannelation of cyclopentanone

Article abstract of DOI:10.1016/00404-0399(50)0958F-

Cyclobutyl phenyl sulfide 2, cyclobutyl phenyl sulfoxide 3 and (SR)- cyclobutyl p-tolyl sulfoxide (SR)-8 have been synthesized and used for the spiroannelation of cyclopentanone. In the most effective sequence, lithiated 3 is added to ketones with formation of β-hydroxy sulfoxides 4a-g, which are ring enlarged and hydrolyzed to cyclopentanones 6a-e and sulfanylcyclopentene 6f, respectively, after reduction to β-hydroxy sulfides 5a-f. In an asymmetric version using (SR)-8, partial racemization during ring enlargement was observed.